No offense, but that's not how Bethesda operates, and I've been here first hand to witness that. If they make DLC, they'll want the target audience to be EVERYONE, not just high levels. Even Bloodmoon and Tribunal followed this, and while incredibly impossible for low level characters (as nearly everything in Morrowind was), it was actually quite manageable to do both expansions with a moderately leveled character, defeating enemies 2.5x your level. Note, this is back during the time of Morrowind, when TES was an RPG and not an action-adventure game with RPG mechanics. Fast forward to Shivering Isles. While at high levels, it certainly presents a much larger challenge than Cyrodiil, it is still possible to roll through on a low level character. I think this expansion pack will operate nearly identically, or maybe moreso like Point Lookout for Fallout 3, where everything is much tougher and still scales with level. You have no experience around here, and likely registered for Skyrim. I'm not saying that registration date has anything to do with it, and I absolutely could be completely wrong, but I'd listen to some of the older members (I originally registered in 2006, I'm talking about 2002-2003 registration dates, here) have to say. They've (we've) been around for the cycle time and time again.
Shivering isles was fully scaled, just like the rest of Oblivion. Gnarls, Grummites, Hungers and the like were all scaled. They had some variants but it functions the same.
Most action RPG's follow suit with the "Good players can defeat stronger monsters", that's what makes them such an appealing genre. It combines tactical and strategical reward of equipment/character development, with player skill. Great players like myself can facefoll an ancient dragon in Skyrim at level 2 with Lesser ward and enough HP enchantments to avoid an instant cinematic dragon-kill.
Also, TES has never really been a "True" RPG. Even back in Daggerfall, it had aspirations of being an action RPG that couldn't because technology couldn't support a satisfying real-time combat with their other desires. So they overstuffed it with design fluff to compensate. (Not that that's a bad thing, but that's all it really is)